The present disclosure relates to a mobile discharge device for battery modules during emergency or service use and a motor vehicle for emergency or service uses which is connected to the mobile discharge device according to the disclosure.
In the case of a service or after an accident, there is a risk owing to the high amount of energy which is stored in drive batteries of electric motor vehicles. Discharging to a low SOC (state of charge) reduces the risk in the event of uncontrolled release of battery energy.
Safe and quick discharge of batteries after an accident is usually not possible since the power contactors of the battery can no longer be closed: if the battery management system (BMS) is still functioning, it will prevent closing of the contactors since it has already established a crash and possibly resultant defects. If the BMS is no longer functioning, the drive unit for the contactors has failed, with the result that the contactors likewise remain open. The open state is the failsafe state for the battery. In the event of an accident, however, hazardous reactions can occur in this state too, for example as a result of pack-internal short circuits, and these reactions should be reduced in terms of their severity by means of a discharge.
In addition, contactors or switches can also be brought out of operation by an accident.
Therefore, nowadays it is usually not possible to discharge a damaged battery without complicated dismantling of the battery and to bring the battery as quickly into a safe state at the site of the accident. It is particularly risky to transport still charged batteries since, during transport, short circuits can be triggered in the battery as a result of movement of torn-away battery components or cooling water which has flowed out, and these short circuits can result in a fire. It is therefore desirable to discharge the battery directly at the site of the accident without moving it before it is transported to a workshop.
WO 03/041208 A1 discloses a method for eliminating risks in connection with lithium-ion batteries using a heating resistor.
KR 102007006000 A discloses an extinguishing system for fighting a fire caused by an accident in modules of secondary batteries.